I don't know if any study has been done on long term projections on the
seals and the massacre. If anyone knows of any, please let me know.
Meanwhile, here are some of my thoughts.

The Newfoundland coastline is very long, easily 1,500 km as the crow
flies, comparable with that of British Columbia or (California + Oregon +
Washington). Considering an average icecap retreat rate along the coast of
X km/year, it will take 1,500/X years for the ice to retreat from St.
John's up to Cape Chidley. So first, X has to be known.

Depending on the time frame, and assuming that the hunt is not stopped,
the sealers could gradually move north to keep up with the retreating ice
if the retreat is slow enough, or be left behind if the retreat is fast
enough, or else the sealers could leap-frog and set up shop at Cartwright,
or Hopedale, or Hebron or even Cape Chidley itself. Whether they would do
this depends on if they would need to stay where they are for they
non-sealing-seasons fishery.

There is also the consideration whether the ice would retreat eastwards
away from land as well as due north. In this case, the sealers may have to
go out way off shore to reach the ice, and there a distance limit as to
how far off shore the sealing boats could go would apply.

In the longer term, the ice in the Northwest Passage will break up, and
large scale commercial navigation will be developed, and the seals will be
more exposed than ever. Greenland will probably play a role in whatever
may develop, including sealing.

As for the seals, I think ecologically they will do better than the
polar bears. The pupping ice will be shifted northward, and the seals will
likely shift north with it, assuming that their food-fish will do
likewise. Already, Atlantic cod is moving northward to invade the habitat
of the Arctic cod.

We should form a long term strategy to safegurad the seals according to
such scenarios. And certainly, we should end the hunt before any of this
progresses too far.